Ground fault interrupter

ABSTRACT

A ground fault interrupter is constructed with a single housing divided into two compartments. One compartment houses an automatic circuit breaker that is manually operable by successive depressions of a slidable operating member, and the other compartment houses a ground fault detector and an electromagnet that is actuated when a ground fault is detected. A lost motion means connects the electromagnet armature to the armature of the magnetic overload trip means of the circuit breaker in a manner such that movement of the electromagnet armature moves the overload armature to trip the circuit breaker, but movement of the overload armature will not move the electromagnet armature. In another embodiment a common magnetic frame and armature are used for the magnets in both compartments, and a permanent magnet is utilized to provide pre-excitation to the electromagnet structure.

United States Patent [191 Zubaty et al.

[ Apr. 23, 1974 i 1 GROUND FAULT INTERRUPTER [75] inventors: Martin V.Zubaty, Bellefontaine;

John B. Cataldo, Moorestown, both of NJ.

[73] Assignee: ITE Imperial Corporation,

Philadelphia, Pa.

[22] Filed: Nov. 29, 19 72 [21] Appl. No.: 310,571

Primary Examiner-Harold Broome Attorney, Agent, or FirmOstrolenk, Faber,Gerb &

Soffen [57] ABSTRACT A ground fault interrupter is constructed with asingle housing divided into two compartments. One compartment houses anautomatic circuit breaker that is manualiy operable by successivedepressions of a slidable operating member, and the othercompartrnenthouses a ground fault detector and an electromagnet that is actuatedwhen a ground fault is detected. A lost motion means connects theelectromagnet armature to the armature of the magnetic overload tripmeans of the circuit breaker in a manner such that movement of theelectromagnet armature moves the overload armature to trip the circuitbreaker, but movement of the overload armature will not move theelectromagnet armature.

in another embodiment a common magnetic frame and armature are used forthe magnets in both compartments, and a permanent magnet is'utilized toprovide pre-excitation to the electromagnet structure.

7 Claims, 13 Drawing Figures WWW APR 2 3 mm SHEET 2 BF 2 GROUND FAULTINTERRUPTER Conventional circuit breakers for home and light industrialapplications usually have thermal and magnetic fault responsive tripmeans to automatically open the main contacts of the circuit breakerwhen excessively high current flows through the main contacts. Theprotection afforded prevents damage to load wiring and to the load.However, this does not insure that low magnitude fault currents causedby high resistance faults to ground will not result in injury topersonnel or start fires.

In order to obtain protection against the aforesaid low magnitudefaults, so-called ground fault interrupters have been provided to extendthe protection afforded. by conventional circuit breakers. A typicalground fault interrupter is described in U.S. Pat. No.

3,473,091, issued Oct. 14, 1959, to A. R. Morris et al.

fora Ground Leakage Differential Protective Apparatus.

In accordance with the instant invention, an insulated housing isdivided into two compartments, one of which contains a conventionalpush-push type singlepole circuit breaker having thermal and magneticmeans for automatic tripping under high current fault conditions. Theother compartment houses the elements for detecting ground faults andgenerating a mechanical force to trip the circuit breaker whenrelatively low current ground faults are present. In one embodiment ofthe instant invention, the ground fault unit includes an electromagnetwith an armature that is connected by an insulating link to the armatureof the circuit breaker magnetic trip. This link provides a lostmotionconnection constructed so that operation of the ground fault magnetmoves the armature of the circuit breaker trip magnet, but energizationof the trip magnet is ineffective .to move the armature of the groundfault magnet so that calibration of the magnetic overload trip device isnot effected by the' ground tripping device. I

In another embodiment of the instant invention the ground fault andcircuit breaker magnet coils are mounted on a common magnetic frameextending into both compartments, with this frame including a singlemovable armature. The coils of the ground fault and overload magnets arewound so that the fluxes generated thereby are in aiding relationship.As an optional feature, one or more permanent magnets may be provided toaid the magnet fluxes.

Accordingly, a primary object of the instant invention is to provide anovel construction for a combination circuit breaker and ground faultprotective device.

Another object is to provide a combination unit of this type in whichthe circuit breaker handle is of the push-push type.

Still another object is to provide a combination unit of this typehaving a lost motion connection between lowing description of theaccompanying drawings in which:

FIG. 1 is a side elevation of a combinationcircuit breaker-ground faultdetector constructed in accordance with teachings of the instantinvention.

FIG. 2 is a plan view of the combination unit of FIG. 1.

FIG. 3 is a cross-section taken through line 33 of FIG. 2, looking inthe direction of arrows 3-3.

FIG. 4 is a cross-section taken through line 4-4 of FIG. 3, looking inthe direction of arrows 4-4.

FIG. 5 is a plan view of the armature for the ground fault trippingmagnet.

FIG. 6 is an end view of the armature of FIG. 5, looking in thedirection of arrows 6--6.

FIG. 7 is a plan view of the insulating link interconnecting the groundfault and overload current tripping armatures.

FIG. 8 is an end view link of FIG. 7, looking in the direction of arrows88.

FIG. 9 is a plan view of the overload current armature.

FIG. 10 is an end view of the armature of FIG. 9,

looking in the direction of arrows 10l0.

FIG. 11 is an electrical schematic showing the combination unit of FIG.1, connected in circuit between a load and a source of electrical power.

FIG. 12 is a view similar to FIG. 3, illustrating another embodiment ofthe instant invention in which a common magnetic frame supports theoperating coils for both the overload current and ground fault trippingelectromagnets.

FIG. 13 is a side elevation of the electromagnets of partition 28divides housing 21 into side-by-side compartments..The left one of thesecompartments, as viewed in FIG. 3, contains the elements of a singlepole so-called push-push circuit breaker" constructed essentially thesame as each pole of the circuit breaker illustrated in U.S. Pat. No.3,075,058 issued Jan. 22, 1963, to E. P. Platz et al. for a Push-PushCircuit Breaker. The right-hand compartment of housing 21, as viewed inFIG. 3, contains the elements of a ground fault protector. Theseelements (not shown) are mounted to printed circuit board 29 and arearranged, for example, in a circuit of the type illustrated in theaforesaid Morris et al. U.S. Pat. No. 3,473,091. Also mounted within theright-hand compartment is ground fault tripping magnet 30 thatisactuated by signals generated in secondary winding 32 and fed throughamplifier 35 of the ground fault detector.

Secondary winding 32 is part of transformer 31 which also includesidentical primary windings 33, 34 connected in series with the neutral37 and hot wires 38, respectively, connecting a.c. source 36 toelectrical load 39. Primary 33 is connected through lead 41 to neutralline 37 that is grounded near source 36. The other end of primary 33 isconnected through lead 42 and line 43 to one terminal of load 39. Theother terminal of load 39 is connected through line 44 to circuitbreaker load terminal 45. Hot line 38 is connected directly from source36 to circuit breaker line terminal 46. The path between terminals 45,46 internal of housing 21 includes load terminal 45 connected to one endof coil 47 of overload tripping magnet 50, through coil 47 and primary34 to one end of overload tripping bimetal 58, through bimetal 58 andmovable contact arm 48 engaged with stationary contact 49 mounted toline terminal 46 at a point thereof internal of housing 21.

Ground fault trip magnet 30 includes ground fault trip coil 84 andmovable armature 52. The latter is connected by insulating link 53 tomovable armature 51 of circuit breaker magnet 50 in a manner such thatmovement of armature 52 is transmitted by link 53 to cause movement ofarmature 51 downward with respect to FIG. 3, or in tripping direction,thereby moving armature latch formation 54 below and clear of latch tip55 on movable contact arm 48 so that main operating spring 56 iseffective to move contact arm 48 about its pivot pin 57, therebyseparating the lower end of movable contact arm 48 from stationarycontact49. The circuit breaker automatic trip means also includesbimetal 58 which upon heating deflects downward with respect to FIG. 3,engaging insulating button 59 mounted to circuit breaker armature 51,causing the latter to move downward to unlatching position.

As fully explained in the aforesaid U.S. Pat. No. 3,075,058, operatingbutton 61, slidably mounted to housing 21, is manually depressible andis constructed so that the circuit breaker main contacts 48, 49 willalternately open and close with successive depressing operations ofbutton 61. In a manner well known to the art, button 62, upon beingdepressed, causes the engagement of spring contact 63 with springcontact 64 to generate a tripping signal in secondary winding 32 oftransformer 31.

As best seen in FIGS. 7 and 8, insulating link 53 is a thin elongatedmember having rectangular cutouts 66, 67, with the latter beingnoticeably elongated in the direction of the longitudinal axis of link53. Ground fault tripping armature 52 (FIG. along one edge thereof isprovided with spaced pivot extensions 71. Lateral extension 72 ofarmature 52 extends into the smaller aperture'66 of link 53. Elongatedaperture 67 of link 53 receives lateral extension 73 of circuit breakermagnet armature 51 (FIG. 9). The latter is provided with pivotextensions 74 projecting from the edge thereof opposite plastic button59. Thus, when coil 84 of ground fault magnet 30 is energized, the rearof armature 52 is moved downward against the force of coil spring 81,with armature extension 72 moving link 53 longitudinally downward. Thiscauses the upper boundary wall of elongated aperture 67 to engagecircuit breaker armature extension 73 thereby moving the rear end ofarmature 51 downward against the force of its coil biasing spring 82 torelease latch tip 55 of movable contact arm 48. It is noted thatenergization of circuit breaker magnet 50 is ineffective to move groundfault armature 52 in that upon energization of magnet 50 causingdownward movement of armature 51, extension 73 thereof is free to traveldownward in elongated aperture 67 without causing movement of link 53.Thus, it is seen that ground fault armature biasing spring 81 does notinfluence the calibration of the magnetic trip for the circuit breakersection.

The first (FIGS. 1-10) and second (FIGS. 12 and 13) embodiments of thisinvention differ in that in the latter both circuit breaker trip coil47, ground fault trip coil 84, and the magnetic cores for each aremounted to a common magnetic frame 85 which extends across bothcompartments of housing 86 for ground fault interrupter 100, and acommon armature 87 extending across both compartments of housing 86 isutilized so that link 83 is eliminated. Naturally, because of the raisedlocation of ground fault trip coil 84 in FIG. 12 as compared to theposition thereof in FIG. 3, printed circuit board 88, carrying theelectrical components (not shown) constituting the ground fault detectoris of a different construction than printed circuit board 29,

and most of the components mounted to board 88 are disposed below magnetcoil 84. In the embodiment of FIGS. 12 and 13, since coils 47 and 84 aremounted to common frame 85, circuit breaker current flowing through coil47 premagnetizes frame 85 to achieve very fast operation of armature 87when coil 84 is energized. The magnetic fluxes generated by currentsflowing in both coils 47 and 84 act in series on common armature 87. Toaccomplish even higher sensitivity and narrow the pickup range,additional magnetic flux is provided by permanent magnet 89 mounted tothe vertical leg of magnetic frame 85. One or both of the cores forcoils 47 and 84 may have permanent magnets. Any of the permanent magnetsmay be adjustable, by repositioning or otherwise, to controlelectromagnet sensitivity.

Although there have been described preferred embodiments of this novelinvention, many variations and modifications will now become apparent tothose skilled in the art. Therefore, this invention is to be limited notby the specific disclosure herein, but only by the appending claims. I

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows.

1. A ground fault protective device including a single housing having apartition separating first and second side-by-side compartments withinsaid housing; an automatic circuit breaker within said firstcompartment; a ground fault detector in said second compartment; saidcircuit breaker including a stationary contact, a movable contact means,latch means for maintaining said movable contact means in an operatingposition, automatic trip means to release said latch upon predeterminedoverload conditions in the circuit being protected by said circuitbreaker, an operating means for moving said movable contact means to acircuit breaker closed position when said movable contact means is insaid operating positionand for moving said movable contact means to acircuit breaker open position when said latch means releases saidmovable contact means; said operating means including an operatingmember biased to normally protrude outward from said first compartment;said operating member being mounted for linear movement and beingmanually depressible so that upon successive manual operations thereofin the same direction, said operating member will actuate said operatingmeans to alternately open and close said circuit breaker; said groundfault detector including a releasing portion connected to said circuitbreaker to release said latch means when a ground fault is detected'bysaid ground fault detector; said automatic trip means including a firstelectromagnet having a first armature and the releasing portion of theground fault detector including a second electromagnet having a secondarmature connected to said first armature for moving the latter torelease said latch means when said second electromagnet is energized; alink interconnecting the armatures and movable linearly in a planegenerally parallel to said partition and generally parallel to movementof said operating member.

2. A device as set forth in claim 1 in which there is a lost motionconnection between said first and second armatures whereby movement ofsaid second armature is effective to move said first armature andmovement of said first armature is ineffective to move said secondarmature.

3. A device as set forth in claim 1 in which the link is adjacent thepartition.

4. A ground fault protective device including housing means definingfirst and second side-by-side compartments; an automatic circuit breakerwithin said first compartment; a ground fault detector in said secondcompartment; said circuit breaker including a stationary contact, amovable contact means, latch means for maintaining said movable contactmeans in an operating position, automatic trip means to release saidlatch upon predetermined overload conditions in the circuit beingprotected by said circuit breaker, an operating means for moving saidmovable contact means to a circuit breaker closed position when saidmovable contact means is in said operating position and for moving saidmovable contact means to a circuit breaker open position when said latchmeans releases said movable contact means; said operating meansincluding an operating member biased to normally protrude outward fromsaid first compartment; said operating member being mounted for linearmovement and being manually depressible so that upon successive manualoperations thereof in the same direction, said operating member willactuate said operating means to alternately open and close said circuitbreaker; said ground fault detector including a releasing portionconnected to said circuit breaker to release said latch means when aground fault is detected by said ground fault detector; said first andsecond armatures constituting different portions of a single armaturemember; said first and second electromagnets including a commonstationary frame to which said armature member is mounted; said firstand second electromagnets including respective first and secondoperating coils mounted to said stationary frame and arranged so thataiding fluxes are generated in said frame by currents flowing in saidoperating coils.

5. A device as set forth in claim 4 in which there is a permanent magnetmeans positioned to generate flux in said core to said those fluxesgenerated by currents flowing in said operating coils of saidelectromagnets.

6. A ground fault protective device including housing means definingfirst and second side-by-side compartments; an automatic circuit breakerwithin said first compartment; a ground fault detector in said secondcompartment; said circuit breaker including a stationary contact, amovable contact, latch means for maintaining said movable contact meansin an operating position, automatic trip means to release said latchupon the occurrence of predetermined overload conditions in the circuitbeing protected by said circuit breaker, an operating means for movingsaid movable contact means to a circuit-breaker closed position whensaid movable contact means is in said operating position and for movingsaid movable contact to a circuit breaker open position when said latchmeans releases said movable contact means; said operating meansincluding an operating member pretruding outward from said firstcompartment; said operating member being manually operable so thatsuccessive manual operations of said operating member will actuate saidoperating means to alternately open and close said circuit breaker; saidground fault detector including a portion connected to said circuitbreaker to release said latch means when a ground fault is detected bysaid ground fault detector; said automatic trip means including a firstelectromagnet having a first armature and the portion of the ground.fault detector including a second electromagnet having a second armatureconnected to said first armature for moving the latter to release saidlatch means when said second electromagnet is energized; said first andsecond armatures constituting different portions of a single armaturemember; said first and second electromagnets including a commonstationary frame to which said armature member is mounted; said firstand second electromagnets including respective first and secondoperating coils mounted to said stationary frame and arranged so thataiding fluxes are generated in said frame by current flow in saidoperating coils.

7. A device as set forth in claim 6 in which there is an adjustablepermanent magnet means positioned to generate flux in said core to aidthose fluxes generated by currents flowing in said operating coils andthereby control sensitivity.

1. A ground fault protective device including a single housing having apartition separating first and second side-by-side compartments withinsaid housing; an automatic circuit breaker within said firstcompartment; a ground fault detector in said second compartment; saidcircuit breaker including a stationary contact, a movable contact means,latch means for maintaining said movable contact means in an operatingposition, automatic trip means to release said latch upon predeterminedoverload conditions in the circuit being protected by said circuitbreaker, an operating means for moving said movable contact means to acircuit breaker closed position when said movable contact means is insaid operating position and for moving said movable contact means to acircuit breaker open position when said latch means releases saidmovable contact means; said operating means including an operatingmember biased to normally protrude outward from said first compartment;said operating member being mounted for linear movement and beingmanually depressible so that upon successive manual operations thereofin the same direction, said operating member will actuate said operatingmeans to alternately open and close said circuit breaker; said groundfault detector including a releasing portion connected to said circuitbreaker to release said latch means when a ground fault is detected bysaid ground fault detector; said automatic trip means including a firstelectromagnet having a first armature and the releasing portion of theground fault detector including a second electromagnet having a secondarmature connected to said first armature for moving the latter torelease said latch means when said second electromagnet is energized; alink interconnecting the armatures and movable linearly in a planegenerally parallel to said partition and generally parallel to movementof said operating member.
 2. A device as set forth in claim 1 in whichthere is a lost motion connection between said first and secondarmatures whereby movement of said second armature is effective to movesaid first armature and movement of said first armature is ineffectiveto move said second armature.
 3. A device as set forth in claim 1 inwhich the link is adjacent the partition.
 4. A ground fault protectivedevice including housing means defining first and second side-by-sidecompartments; an automatic circuit breaker within said firstcompartment; a ground fault detector in said second compartment; saidcircuit breaker including a stationary contact, a movable contact means,latch means for maintaining said movable contact means in an operatingposition, autoMatic trip means to release said latch upon predeterminedoverload conditions in the circuit being protected by said circuitbreaker, an operating means for moving said movable contact means to acircuit breaker closed position when said movable contact means is insaid operating position and for moving said movable contact means to acircuit breaker open position when said latch means releases saidmovable contact means; said operating means including an operatingmember biased to normally protrude outward from said first compartment;said operating member being mounted for linear movement and beingmanually depressible so that upon successive manual operations thereofin the same direction, said operating member will actuate said operatingmeans to alternately open and close said circuit breaker; said groundfault detector including a releasing portion connected to said circuitbreaker to release said latch means when a ground fault is detected bysaid ground fault detector; said first and second armatures constitutingdifferent portions of a single armature member; said first and secondelectromagnets including a common stationary frame to which saidarmature member is mounted; said first and second electromagnetsincluding respective first and second operating coils mounted to saidstationary frame and arranged so that aiding fluxes are generated insaid frame by currents flowing in said operating coils.
 5. A device asset forth in claim 4 in which there is a permanent magnet meanspositioned to generate flux in said core to said those fluxes generatedby currents flowing in said operating coils of said electromagnets.
 6. Aground fault protective device including housing means defining firstand second side-by-side compartments; an automatic circuit breakerwithin said first compartment; a ground fault detector in said secondcompartment; said circuit breaker including a stationary contact, amovable contact, latch means for maintaining said movable contact meansin an operating position, automatic trip means to release said latchupon the occurrence of predetermined overload conditions in the circuitbeing protected by said circuit breaker, an operating means for movingsaid movable contact means to a circuit breaker closed position whensaid movable contact means is in said operating position and for movingsaid movable contact to a circuit breaker open position when said latchmeans releases said movable contact means; said operating meansincluding an operating member pretruding outward from said firstcompartment; said operating member being manually operable so thatsuccessive manual operations of said operating member will actuate saidoperating means to alternately open and close said circuit breaker; saidground fault detector including a portion connected to said circuitbreaker to release said latch means when a ground fault is detected bysaid ground fault detector; said automatic trip means including a firstelectromagnet having a first armature and the portion of the groundfault detector including a second electromagnet having a second armatureconnected to said first armature for moving the latter to release saidlatch means when said second electromagnet is energized; said first andsecond armatures constituting different portions of a single armaturemember; said first and second electromagnets including a commonstationary frame to which said armature member is mounted; said firstand second electromagnets including respective first and secondoperating coils mounted to said stationary frame and arranged so thataiding fluxes are generated in said frame by current flow in saidoperating coils.
 7. A device as set forth in claim 6 in which there isan adjustable permanent magnet means positioned to generate flux in saidcore to aid those fluxes generated by currents flowing in said operatingcoils and thereby control sensitivity.